[PS] variance

semester4/ps/ps-rb/util/helpers.tex

@@ -60,6 +60,8 @@
 \def \P{\mathbb{P}}
 \def \F{\mathcal{F}}
 \def \E{\mathbb{E}}
+\def \I{\mathbb{I}}
+\def \V{\mathbb{V}}
 
 % Titles
 \def \definition{\colorbox{lightgray}{Def} }